Hello I am thinking about building a wet dry vacuum cleaner using the cage and the blades from an office fan, using a blender motor, all mounted on a plastic trash bin. As of now I need to come up with a filter system. Is there anything I should change or add, or is this project just bound to fail and waste my time? ,

It is worth a try if you have the materials and if you are looking for a fun project, but if you need to buy the items, it may just be less expensive to buy a used wet dry vacuum. It may also be difficult to build this from scratch with household materials and have it work and seal properly for good vacuum.

Well, is say it would only cost about 30-40 dollars because I already have a blender with broken blades.
This project is only really being made because I used to have an old Craftsman Home N Shop Permanex vacuum (which this design is based on). It had beautiful suction and was 27 gallons and was just a metal fan mounted on a large plastic bin which I bought new at an estate sale. It lasted for 15 years until I gave it to a friend who works with a large construction company. Anyway, enough rambling. I want to build this because since I gave a way the last vac, I have went through 4 crappy shop vac brand vacs all bought from the same lowes. I just want something that won't burn up in a few months
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Oh I can certainly understand that. It does seem that the newer wet/dry vacs do not last nearly as long as the older versions did. Although, you can still find used ones at thrift stores that are perfectly good.

A newer shop vac that was given to me without the hose, being in the business I am in I have parts all over for creativity. I grabbed a domel motor that was laying around from an Electrolux oxygen several rubber gaskets and fastened it to the machine with a bracket that I found. The machine has 110" of water lift, quite the amount of airflow. And better yet it's quiet enough that it isn't heard throughout the building. I have used it to clean out a drain that has been plugged for the last 8 months and it definitely took care of the clog, the machine is used as my main bench vac while sitting in another room and being used with a 35' hose and a 5 gallon shop vac bag. I do recommend that if you are to do this project you should find a motor suitable for the job and make sure you ground it in the event it is used for wet pick up. As far as filtering goes, for dry pick up I would use a bag, if you can make a device or can somehow adapt a shop vac filter cage to your unit a paper pleated HEPA filter should be fine. This is the motor I use in my machine and it runs on average 10 hours a week. Never overheats and seems to be pretty durable for the abuse and use it gets.

I wonder if an old Bissel little green motor would better as it is already grounded and it designed to handle wet pickups, but I'm not sure how powerful the suction would be though. I see them for sale at my local goodwill a lot for under 10$.

As David stated it wouldn't be much, with the domel I posted you could mount it, run a 3 prong cord and switch to it and be all set. Gasket the lid of the cab you are using to create the seal. The thing is you will need a heavy duty can as a thin can will suck inwards. The advice I offered will create a very powerful machine with a lot of capabilities.

The old Dyson motor will work well... due to the lack of cyclones on your design you should be able to get decent airflow out of that motor. In the event it doesn't work I'm sure I can get you the same motor I have for the cost of shipping.
Mike

I would NOT try to use an office fan propeller on a blender motor-the fan was not designed to be used at the speed a blender motor runs at-and no doubt you will overheat the blender motor.Just look for a used wet dry vacuum-or buy one.They are not that expensive.Safer and better than trying to make your own.Lowes,Home Depot,Menards,Sears carry a line of low cost wet dry "shop" type vacuums.

Yes but as I said I would just use an old dyson motor instead. Besides, like I mentioned above I have no luck with those new model Shop-Vac, Craftsman, or Ridgid brand vacs. I bought 4 new shop vac branded vacuums from the same lowes. They are the gray topped blue bottomed models, all different gallon sizes. All have stopped working within the past 2 months of buying the first. I have tried my friend's Craftsman and Ridgid Vacs, but they both are cheaply mass produced with switches that break , manufactured in China. As Much as I would love to have and old Craftsman Wet Dry Vacuum, I need something larger than most conventional vacs, similar to the Home n Shop Vac I used to own. I need this large drum size for dust collection and the occasional wet and dry pickup here and there, as I cannot afford a good dust collector. As I said I would love a new permanex vac, but they are rare and hard to come by these days.

Since you appear to use a Shop type vacuum frequently-consider investing in a metal drum -or thicker plastic drum commercial machine.These have heavier duty motors,cords,switches ,and containers to withstand commercial,heavy use.Shop Vac does make commercial machines but you may have to purchase from Grainger or McMasterCarr.And the hoses and attachments are heavier duty than the light plastic tools sold with Lowes,HD,Menards vacuums-those being for home use.

Another thought-the Dyson motor may not withstand being used to pick up liquids-and perhaps even unsafe for this application since its a flow-thru motor.The better quality WD vacuums use a full bypass motor-the cooling airstream is separate from the suction airstream.

If made properly the Dyson motor will fair rather well as it won't have nearly as much resistance. The way I made my machine it seems to be fine for wet pick up on his machine the float might have to be made to work with a lower level of water.

I don't mean the SV 55 gal drum topper machine-there are others worth considering-and not just Shop-Vac.I don't fully understand what the vacuum is being used for-just a dust collector-there are dust collectors out there that would be less expensive if you are just using the machine to collect dust from power tools.Shop Smith makes such a machine.Look on their website.

I wonder if a leaf blower/vac fan could be used. I'm not sure about using it for wet pick-up though. I still think it is cheaper to just buy something that was intended for the purpose which it was intended.